Rail Accident Investigation Branch Says CCTV Showed Track Geometry Irregularity Before Derailment

The Rail Accident Investigation Branch (RAIB) said CCTV images showed the "track geometry irregularity" existed before the incident, which injured 30 people. The watchdog published an image that appeared to show the track had buckled — something that can happen in high temperatures — before the Southern train derailed. The RAIB said its investigation was taking weather conditions into account, as well as the status of the track, embankment, condition of the train and the effectiveness of any measures taken to mitigate the hot temperatures.

The report said there had been "a sustained period of hot and dry weather" and that the ambient air temperature at the time was about 27C, according to the nearest weather station to the site. In a joint statement, Network Rail and Greater Thameslink Railway (GTR), which runs Southern, said they were "very sorry that this happened on our railway". "We also recognise the ongoing impact the incident has had on customers, local communities and railway colleagues, said Lucy McAuliffe, Sussex route director at Network Rail, and John Whitehurst, chief executive at GTR. "Safety is and will always remain our highest priority.